Keyboard actuated paper insertion and ejection mechanism

ABSTRACT

A typewriter mechanism responsive to an operator-controlled key automatically inserts a sheet of paper between the platen and paper bail in preparation for printing by raising the bail as the platen-entrained paper advances with the platen and then restoring the bail when the paper has passed between the platen and the bail.

BACKGROUND

This invention relates to an automatic, keyboard-operated paperinsertion and ejection mechanism for typewriters, calculators or similaroffice machines. While the invention is described and claimed inconnection with a typewriter, the invention is equally applicable foruse in calculators or similar office machines.

Modern office machines perform various machine functions by automatic,keyboard-controlled mechanisms which were previously performed bymanually operated mechanisms. It has been found that many of themanually operated mechanisms cannot be adapted to keyboard-controlledoperation, but must be replaced by specially suited automaticmechanisms. Two such functions are the paper insertion function and thepaper ejection function.

To automatically feed the paper to printing position in response to akeyboard-mounted switch, the machine mechanism must lift the paper bail,which is normally biased into engagement with the platen, off the platenso that the paper may be readily inserted between the platen and thebail-mounted pressure rolls as the platen-entrained paper advances withthe platen. To complete insertion of the paper, the paper bail must berestored to apply pressure to the platen-entrained paper. Similarly, inresponse to a keyboard switch-actuated signal, the mechanism must alsolift the paper bail to eject and allow withdrawal of the paper frombetween the bail and platen when printing has been completed. Thisrequires a precision connection between the paper feed and the liftingmechanism, which is most conveniently achieved by a geared connectionwith the platen. However, the lifting and restoring mechanism must bedisengaged from the paper feed mechanism during the line-indexingoperation.

SUMMARY OF THE INVENTION

Briefly, the invention of an automatic, keyboard-controlled paperinsertion mechanism for typewriters, calculators or similar machines,inserts the paper between the platen and the paper bail in preparationfor printing.

The mechanism includes a counter gear wheel meshing with the teeth of agear wheel fixed to the platen, a one-cycle clutch for selectivelyentraining a camming pin for rotation with the counter gear wheel, acontrol lever guidedly mounted in the typewriter and having a cammingsurface for cooperation with the camming pin, a link connecting thecontrol lever with the paper bail, and an electromagnet connected to adetent lever for selective engagment of the clutch. The clutch includesa clutch wheel fixed to the counter gear wheel and an entrainer discmounted concentrically with the counter gear wheel. A clutch pawl ispivotally mounted on the entrainer disc, is constantly urged intoengagement with the clutch wheel by a spring mounted on the entrainerdisc, and is retained disengaged from the clutch wheel by a detentsurface formed on the clutch pawl which cooperates with the detentsurface of the detent lever.

On command from a keyboard mounted switch starting the paper insertionprogram, rotation of the platen and the meshing counter gear wheel isinitiated, and the electromagnet is energized, releasing the pawl toengage the clutch wheel and entraining the entrainer disc for rotationwith the counter gear wheel. As the counter gear wheel and platen rotatethrough a given angular distance, the entrainer disc carries the cammingpin into engagement with the camming surface on the control lever topivot the link and paper bail away from the platen and allow the paperto be inserted between the platen and the bail. As the platen andcounter gear wheel continue to rotate, the camming pin acts againstanother camming surface associated with the control lever to pivot thelink to restore the paper bail to the platen. With continued rotation ofthe platen and counter gear wheel, the detent surface of the pawlencounters the detent surface of the detent lever, disengaging theentrainer disc from the counter gear wheel at the end of a revolution ofthe entrainer disc. The platen continues to be indexed by the steppingmotor to move paper to a desired printing line. Since the insertionmechanism is disengaged from the platen driven gear wheel, subsequentline indexing may take place without disturbing the engagement betweenthe paper and the platen.

Additionally, the mechanism may be used to eject and allow withdrawal ofpaper from between the platen and the bail after printing has beencompleted.

OBJECTS OF THE INVENTION

An object of the invention is to insert paper into printing positionbetween the platen and paper bail of a typewriter by an automatickeyboard-controlled mechanism.

Another object of the invention is to insert paper into printingposition between the platen and paper bail of a typewriter by anautomatic keyboard-controlled mechanism which lifts the bail off theplaten to allow the paper to pass between the platen and thebail-mounted pressure rolls and which restores the paper bail to theplaten to hold down the platen-entrained paper.

Yet another object of the invention is to insert paper into printingposition between the platen and paper bail of a typewriter by anautomatic keyboard-controlled mechanism which is disengaged during lineindexing operation of the typewriter.

Another object of the invention is to eject and allow withdrawal ofpaper from between the paper bail and the platen of a typewriter by anautomatic, keyboard-controlled mechanism.

Yet another object of the invention is to provide an automatic,keyboard-controlled mechanism which inserts paper to printing positionbetween the platen and paper bail of a typewriter and additionallyejects the paper from between the platen and paper bail.

Other objects and many of the attendant advantages of the presentinvention will become apparent to those skilled in the art from areading of the following detailed description taken in conjunction withthe accompanying drawing wherein like reference characters designatelike parts and wherein:

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a side view of the keyboard-controlled feed, insertion andejection mechanism of the invention in rest position, ready forreceiving a sheet of paper;

FIG. 2 is a side view of the keyboard operated feed, insertion andejection mechanism of the invention immediately after the operator haspressed the paper insertion key;

FIG. 3 is a view similar to the views of FIGS. 1 and 2 showing themechanism of the invention lifting the paper bail off the platen; and

FIG. 4 is a view similar to the views of FIGS. 1-3 showing the mechanismof the invention restoring the paper bail toward the platen, the paperhaving been fed to printing position, shortly before the end of thecycle of the mechanism.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, the paper insertion and ejection mechanism of theinvention, generally indicated by reference numeral 10 includes a paperinsertion and ejection program start means 11 which comprises a keyboardmounted operator controlled key which controls the operation of anelectromagnet 52 and a stepping motor 13 mechanically connected with ashaft 14 by conventional means not shown. A platen 12 is secured toshaft 14 which is mounted for rotational movement on the side frames(not shown) of the typewriter. Rigidly fixed to platen 12 is a gearwheel 16 having teeth 18 which continuously mesh with cooperating gearteeth 20 on counter gear wheel 22 mounted for rotational movement abouta stud 24 mounted on the side frame of the typewriter. A clutch wheel 26having teeth 28 is fixed to counter gear wheel 22 and is mounted forrotation about stud 24 with the counter gear wheel. An entrainer disc 30mounted for free rotation about stud 24 mounts a fixed projectingcamming pin 32 on one side and a clutch pawl 34 on the opposite side,pawl 34 being freely pivotable about a fixed pivot 36.

Clutch pawl 34 is provided with an inwardly projecting tooth 38 and adetent surface 40 and is continuously urged inwardly under the force ofspring 42 connected with the clutch pawl and mounted on entrainer disc30.

In the rest position illustrated in FIG. 1, detent surface 40 of clutchpawl 34 cooperates with a mating detent surface 44 on a detent lever 46which is pivotally mounted on a side frame fixed pivot 48. Detent lever46 is spring-loaded toward clutch pawl 34 by side frame mounted spring50, is pivotally secured to the actuating arm 51 of electromagnet 52,and is provided with inner and outer limit legs 54, 55 which cooperatewith a side frame fixed stop 56 to limit the displacement of detentsurface 44 of the detent lever.

A control lever 58 has a guide pin 60 and guide slot 62 which cooperatewith a side frame fixed guide slot (not shown) and side frame fixedguide pin 64, respectively, to allow control lever 58 to translatehorizontally in the machine frame, as shown in FIGS. 1-4. Control lever58 is provided with an inwardly projecting camming surface 66 forcooperation with camming pin 32 of entrainer disc 30, as explainedhereinafter, and is provided with a pivot 68 pivotally mounting arelease pawl 70, which is constantly urged against a control lever fixedpin 71 by release spring 72 fixed to control lever 58. A connecting link74 is pivotally connected with control lever 58 at pivot 76 and with apaper bail 78 at pivot 80. Paper bail 78 has bail arms 82 fixed to a bar84 mounting a pressure roll or rolls 86 and is biased either towardplaten 12 or away from the platen under the force of an over-centerspring (not shown), as is known in the art, attached to bail 78 atopening 88.

Mounted for pivotal movement on side frame fixed guide pin 64 is adetent lever 90 having a projecting detent 92 for cooperation with adetent recess 94 (FIGS. 3 and 4) formed in entrainer disc 30. Detentlever 90 is urged inwardly toward entrainer disc 30 under the force of aside frame fixed spring 96.

In operation, the mechanism 10 of the invention is initially in the restposition shown in FIG. 1. The typewriter operator positions a piece ofpaper 98 into the nip between platen 12 and feed rollers (not shown) asis conventional in the art and which forms no part of the invention. Theoperator then actuates the paper insertion program start means 11 bypressing an "insert" key located on the typewriter keyboard, generatinga signal which starts stepping motor 13 connected with shaft 14 ofplaten 12 for programmed rotation of the platen in the direction ofarrow A of FIG. 1 and which simultaneously energizes electromagnet 52drawing electromagnet armature 51 inwardly, or in the direction of arrowB of FIG. 1.

As platen 12 rotates in the direction of arrow A, feeding paper 94around the platen, platen gear teeth 18 rotate counter gear wheel teeth20 and counter gear wheel 22 in the opposite direction. The paper isguided around the platen by feed rollers and a paper tray (not shown) asis conventional in the art and which form no part of the invention. Asarmature 51 of electromagnet 52 is drawn inwardly to the position shownin FIG. 2, detent lever 46 pivots about pivot 48 in the direction ofarrow B until inner limit leg 54 of the detent lever is blocked by stop56, releasing detent surface 40 of clutch pawl 34 from detent surface 44of detent lever 46. After being released, clutch pawl 34 is drawninwardly under the force of spring 42 and clutch pawl tooth 38 engagesthe appropriate tooth of teeth 28 of clutch wheel 26, rotating withcounter gear wheel 22, thus entraining entrainer disc 30 to rotate withcounter gear wheel 22. Detent lever 46 is urged inwardly against theouter surface of clutch pawl 34 by spring 50 and when the clutch pawlhas rotated a sufficient distance, detent lever 46 is restored to theposition of FIG. 1 with the outer limit leg 55 of the detent leverretained against stop 56.

As platen 12 and counter gear wheel 22 rotate and feed platen entrainedpaper 98 in preparation for insertion between the platen and pressurerolls 86, entrainer disc 30 rotates and carries camming pin 32 intocontact with camming surface 66 on control lever 58, as shown in FIG. 3.Continued rotation of platen 12, counter gear wheel 22, and entrainerdisc 30 carrying pin 32 translates control lever 58, guided by pin 60and slot 62, toward paper bail 78, driving connecting link 74 to pivotpaper bail 78 away from the platen against the force of the over-centerspring connected to the bail at opening 88, lifting pressure rolls 86from platen 12. Continued rotation of entrainer disc 30 pivots bail 78and opening 88 to drive the over-center spring over-center, retainingbail 78 in the open position shown in phantom in FIG. 3. Continuedrotation of entrainer disc 30 brings camming pin 32 into contact withrelease pawl 70, pushing the release pawl, which is locked in positionby pin 71, away from the platen, carrying control lever 58 andconnecting link 74, and pivoting paper bail 78 toward the platen, asshown in FIG. 4. Pressure rolls 86 are thus lifted off platen 12 duringa predetermined portion of the angular path of the platen, allowing thepaper to be inserted between the pressure rolls and the platen, and arereturned to the platen to hold the inserted paper in position inpreparation for printing.

As entrainer disc 30 continues to rotate, camming pin 32 drives therelease pawl 70 and control lever 58 away from paper bail 78, connectinglink 74 pivots the paper bail toward the platen until the over-centerspring retained in opening 88 is driven back over-center, urging thepaper bail, bar 84, and pressure rolls to frictionally engage paper 98against platen 12. Continuing rotation of clutch wheel 26 and entrainerdisc 30 brings detent surface 40 of clutch pawl 34 into contact withmating detent surface 44 of restored detent lever 46, and continuedrotation of clutch wheel 26 pivots the clutch pawl outwardly about pivot36, disengaging clutch pawl tooth 38 from teeth 28 of clutch wheel 26,and ending rotation of entrainer disc 30. Detent 92 of inwardly urgeddetent lever 90 cooperates with detent recess 94 (FIGS. 3 and 4) inentrainer disc 30 to insure that the entrainer disc comes to rest inpredetermined angular position at the end of each insertion cycle.

Stepping motor 13 continues rotating platen 12 and counter gear wheel 22an incremental distance, insuring that the counter gear wheel isdisengaged from the clutch pawl, and the stepping motor is thendeactivated, terminating the paper insertion program with the paperinsertion mechanism returned to the rest position shown in FIG. 1 andthe paper inserted between the platen and the paper bail, and lineindexed in printing position. Typing may now begin andkeyboard-controlled line indexing may now take place without disturbingthe engagement between the paper bail and the platen-entrained papersheet.

To eject paper 98 from between the platen and the paper bail, theidentical mechanism operation sequence is followed, with the typewriteroperator initiating the paper ejection program by pushing the keyboardmounted "insert" key and then removing the paper when it is releasedfrom the platen and associated rollers and when the mechanism of theinvention lifts the paper bail and pressure rolls away from the platen.

The invention claimed is:
 1. In a typewriter having a rotatable platenand an associated paper hold down bail pivotally mounted for movementbetween a closed position in rolling contact with said platen and to anopen position spaced from said platen,energizable motor means connectedto rotatably index said platen to control movement of a sheet of paper,a first clutch part rotatably driven by said platen, a second rotatableclutch part selectively engageable with and driven by said first clutchpart and having a camming pin, a solenoid, means for coupling over aplaten revolution said first and second clutch parts upon energizationof said solenoid, a control lever connected to said paper bail andpositioned to be driven by said camming pin to pivot said paper bail toopen and closed positions in each clutch cycle, and operator controlledmeans for energizing said motor means and for energizing said solenoid.2. In a typewriter as recited in claim 1, said coupling means includinga pawl pivotally mounted on said second clutch part and normally biasedto engage said first clutch part thereby to couple said first and secondclutch parts,said solenoid having an armature normally positioned tomaintain said pawl disengaged and to release said pawl when saidsolenoid is energized.
 3. In a typewriter as recited in claim 2, saidcontrol lever being mounted for translating movement and having firstand second camming surfaces located in the path of and operative by saidcamming pin, to move said control lever in bail opening direction andbail closing direction in each revolution of said clutch.
 4. In atypewriter as recited in claim 3, said motor means comprising a steppingmotor and wherein said stepping motor and solenoid are simultaneouslyenergized by said keyboard mounted means, said solenoid being energizedmomentarily and said stepping motor being energized over a predeterminedprogrammed interval.